This invention relates to foam dispensers and more particularly, it concerns improvements in foam generating and dispensing devices generally constituted by a cap assembly attachable to a collapsible receptacle or bottle containing a formable liquid and air such that upon forced collapse of the bottle walls, a mixture of air and liquid is dispensed as foam through an outlet nozzle in the cap assembly.
The prior art relating to foam dispensers is quite highly developed as demonstrated by the numerous patents and published disclosures as well as by the vast array of commercially available foam product dispensers. In general, such foaming devices may be characterized as falling in one of two basic types; namely, foam dispensing devices which carry a supply of pressurized gas to be mixed with the foamable liquid or manually actuated devices in which the pressure required to dispense foam is developed by collapsing a resilient receptacle or syringe-type pumping device. The present invention is concerned principally though not exclusively with foam dispensing devices of this latter or manually actuated type.
The functional components required for satisfactory operation of manually actuated foam generating and dispensing devices are well known. In addition to the collapsible bottle and discharge nozzle establishing cap assembly, provision must be made for mixing air and foamable liquid under conditions which will produce foam of predictably uniform consistency on forced collapse of the bottle to discharge foam through the nozzle. It is well known in the prior art that such conditions are established by discharging the air and formable liquid through a porous element of sponge-like material providing minute tortuous passages in which highly turbulent flow of the liquid and air effect the appropriate mixing and homogenization of the discharged foam. See, for example, U.S. Pat. No. 2,680,010 issued June 1, 1954 to F. X. Dubay; U.S. Pat. No. 3,422,993 issued Jan. 21, 1969 G. L. Boehm et al. and U.S. Pat No. 3,709,437 issued Jan. 9, 1973 to H. E. Wright.
Although such prior foam generating and dispensing devices have shown promise, their incorporation as cap assemblies for collapsible bottles have presented obstacles to widespread commerical use in part because of excessive manufacturing costs relative to the cost of competing alternatives and in the achievement of rapid recovery of the bottle or receptacle for containing the foamable liquid and air after forced collapse for the discharge of foam through the nozzle of the cap assembly. The excessive costs are believed due primarily to the number of individual parts which have been required in prior devices as well as the time involved in their assembly. The achievement of rapid recovery of the bottle after forced collapse thereof is deterred also in good measure by unwanted manufacturing costs inasmuch as acceptable recovery rates require a provision for one-way valving to allow for the free return of air to the bottle interior without impairing pressurized containment of the air for the foam generating and discharging operation. Because of these and other problems associated with manually actuated foam generating and discharging devices, there has been a trend in the industry to the use of more expensive devices, of the type in which a supply of pressurized gas is carried in the receptacle of foamable liquid with the added costs being passed onto the consumer.